1). Field of the Invention
This invention relates generally to a method and system for laser marking an article, and more specifically to a manner according to which the system is calibrated and used.
2). Discussion of Related Art
Laser marking systems are often used to mark articles with desired patterns before being shipped to a customer. Such a pattern may, for example, be the name of a manufacturer or a serial number.
A laser marker system usually has a frame, a laser, a galvo head, and an article holder, mounted to the frame. The laser generates a laser beam that is directed through the galvo head onto a marking surface of an article that is held by the holder. The galvo head has mirrors and motors that can manipulate the laser beam so that a focal point thereof moves in x- and y-directions. A galvo head also has a processor and memory. A vector set of instructions is stored in the memory and is used by the processor to manipulate the mirrors to mark a desired pattern on the article.
Factory calibration data is also stored in the memory of the galvo head. The factory calibration data is created at a factory where the system is assembled. The galvo head is calibrated so that the focal point of the laser beam is at a reference position (x0;y0).
It has been found that the factory calibration data is not always sufficiently accurate for all purposes, or may also “shift” over a period of time due to tolerances that creep into the frame or the holder. As such, the reference focal point of the laser beam is not at the position (x0;y0) according to the factory calibration data, but instead at new position (x1;y1). A pattern marked on an article will, accordingly, be shifted from the position (x0;y0) according to the factory calibration data to the new position (x1;y1).